| 摘要 |
PURPOSE: To obtain the charging to a peak voltage by connecting an FET switch to a filter capacitor in series, avoiding the charging of the capacitor at the voltage higher than the required voltage for the following load and recharging the filter capacitor with the instantaneous voltage at the outing of a rectifier, at the normal power supply feeding. CONSTITUTION: An AC voltage is rectified with rectifying diodes D1 -D4 . The output is connected to voltage dividers R1 and R2 . An SCR Q1 is triggered through a Zener diode D5 by the divided voltage outputs. Thus, a Zener diode D6 is shorted. A turn-on drive voltage for an FET switch Q2 is removed, and the voltage is turned off. As a result, the charging or a filter capacitor C1 is stopped. In the meantime, an insulating diode D7 decouples the voltage of the stored charge in the film C1 from the input voltage dividers R1 and R2 and from the anode of the SCR Q1 . Thus, the SCR Q1 is securely turned off at the terminal point of each rectifying half frequency.
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